A typical gas combusting furnace system includes a furnace burner contained in a combustion chamber for generating heat, means for transferring the heat from the combustion chamber to the heated space, and means for controlling the operation of the burner. A typical furnace burner of the premix type, where fuel and air are mixed prior to introduction into the combustion chamber, includes a chamber wherein gas and air are mixed and then forced by a single speed, motor operated blower to the combustion chamber. Such furnaces are commonly referred to as "power burners" because of the forcible introduction of the gas and air mixture into the combustion chamber. In a typical premix type furnace burner, the mixture of gas and air is directed into the combustion chamber through a burner element such as a burner plate having a plurality of relatively small apertures.
Ignitors commonly used in power burner systems comprise an electrically heated hot surface element mounted adjacent the combustion side of the burner plate. The ignitor is positioned parallel to the burner screen of the power burner and perpendicular to the stream of the gas which is to be ignited. Screws are used to hold the ignitor in place, with the screws being hand torqued to specification to prevent breaking the ignitor bushing. High temperature gaskets must be used to seal the ignitor to the burner plate, since the junction temperatures between the ignitor and the burner cap can be as high as 1050 F.
Conventional ignitors are highly susceptible to breakage and failure because of the exposure to high operating temperatures. Breakage of the lead-in electrical wires due to prolonged exposure to extreme operating temperatures is a particular problem. Moreover, conventional ignitors are difficult to replace because of their alignment on the combustion side of standard burner plates. The entire burner assembly often needs to be disassembled to reach and replace the ignitor. Heretofore, these problems have been accepted as the unfortunate consequence of having to place the ignitor tip in the area where furnace fuel combustion takes place. An ignitor assembly that positioned the ignitor tip of an ignitor assembly at the desired point of combustion, but was nevertheless isolated in large measure from the extreme temperatures generated by ignition, and which, at the same time, could be easily accessed for repair or replacement, would provide decided advantages.